An X ray diagnostic apparatus includes an X ray tube generating X rays, a first detector detecting the X rays, at least one second detector arranged in front of a first detection surface of the first detector and including a second detection surface narrower than the first detection surface and indicator points provided on a rear surface of the second detection surface, a projection data generation unit generating first projection data based on an output from the first detector, and a positional shift detection unit detecting a positional shift of the second detector relative to the first detector in accordance with an imaging direction by using the first projection data and a predetermined positional relationship between the points and detection elements in the second detector.
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1. An X-ray diagnostic apparatus, comprising: an X-ray tube configured to generate X-rays; a first detector configured to detect the X-rays; at least one second detector arranged in front of a first detection surface of the first detector and including a second detection surface narrower than the first detection surface and a plurality of indicator points provided on a rear surface of the second detection surface; projection data generation circuitry configured to generate first projection data based on an output from the first detector; and positional shift detection circuitry configured to detect a positional shift of the second detector relative to the first detector in accordance with an imaging direction by using the first projection data and a predetermined positional relationship between the indicator points and a plurality of detection elements in the second detector.
An X-ray imaging system uses an X-ray tube to generate X-rays and a first detector to capture the main X-ray image. A second, smaller detector with higher resolution is placed in front of the first. This second detector has indicator points (markers) on its back. The system calculates initial image data from the first detector and then detects the position of the smaller detector relative to the larger one. It does this by using the initial image data and the known positions of the markers on the second detector relative to its own detection elements.
2. The apparatus according to claim 1 , wherein the projection data generation circuitry is further configured to generate the first projection data in association with rotational imaging of performing imaging while rotating, along a predetermined orbit around a predetermined rotation axis, the X-ray tube, the first detector, and the second detector, and to generate second projection data based on an output from the second detector in association with the rotational imaging with respect to an object, and the apparatus further comprises positional shift correction circuitry configured to correct the positional shift of the second projection data by using the imaging direction in the rotational imaging and the positional shift, and reconstruction circuitry configured to reconstruct volume data based on the corrected second projection data.
The X-ray system described previously performs rotational imaging, where the X-ray tube and both detectors rotate around a subject. The system generates image data from both detectors during this rotation. Because the smaller detector might shift, the system corrects its image data using the measured positional shift and the rotation angle. Finally, the corrected image data from the smaller, higher-resolution detector is used to reconstruct a 3D volume image of the subject.
3. The apparatus according to claim 2 , further comprising a memory to store a first correspondence table used for orbit correction of correcting an orbit shift of the first detector relative to the orbit in accordance with the imaging direction, wherein the positional shift correction circuitry is further configured to generate a second correspondence table used for correction of the positional shift with respect to the imaging direction, and to correct the second projection data by using the first correspondence table and the second correspondence table.
The rotational X-ray system described previously includes a memory storing a lookup table to correct for any wobble of the larger detector's orbit. The system also creates another lookup table that corrects the smaller detector's positional shift based on the rotation angle. The smaller detector's image data is corrected using *both* the orbit correction table and the positional shift correction table for improved accuracy.
4. The apparatus according to claim 3 , wherein the positional shift detection circuitry is further configured to detect the positional shift before the rotational imaging with respect to the object, and the positional shift correction circuitry is further configured to generate the second correspondence table before the rotational imaging with respect to the object.
In the X-ray system previously described, the system measures the positional shift of the smaller detector *before* the rotational imaging scan begins. The lookup table for positional shift correction is generated *before* the scan based on this initial measurement. This ensures the system has accurate shift data before reconstructing the 3D image.
5. The apparatus according to claim 3 , wherein the positional shift detection circuitry is further configured to detect the positional shift during the rotational imaging, and the positional shift correction circuitry is further configured to generate the second correspondence table based on the detected positional shift.
In the X-ray system previously described, the system measures the positional shift of the smaller detector *during* the rotational imaging scan. The lookup table for positional shift correction is generated *during* the scan based on these continuous measurements. This allows for dynamic correction if the detector shifts during the procedure.
6. The apparatus according to claim 3 , wherein the second projection data is projection data obtained in a predetermined imaging direction different from the imaging direction in the second correspondence table, the positional shift correction circuitry is further configured to interpolate a positional shift corresponding to the predetermined imaging direction by using two imaging directions adjacent to the predetermined imaging direction, the predetermined imaging direction, and the two positional shifts respectively corresponding to the two imaging directions in the second correspondence table, and to correct the second projection data by using the interpolated positional shift, and the reconstruction circuitry is further configured to reconstruct volume data based on the corrected second projection data.
In the X-ray system previously described, if the needed rotation angle isn't directly in the lookup table, the system estimates the positional shift for that angle. It uses the positional shifts from two nearby angles in the table to interpolate the shift. This estimated shift is then used to correct the smaller detector's image data, and that corrected data is used to create the final 3D image.
7. The apparatus according to claim 2 , wherein the rotational imaging is executed while maintaining a field of view covering a region which covers a detection surface of the second detector and is narrower than a detection surface of the first detector.
The rotational X-ray system previously described ensures the X-ray beam's field of view (the area being scanned) remains focused. Specifically, it maintains a view that covers at least the area of the smaller, high-resolution detector, but is smaller than the area of the larger detector. This optimizes X-ray usage and minimizes unnecessary exposure.
8. The apparatus according to claim 1 , wherein the projection data generation circuitry is further configured to generate the first projection data in association with rotational imaging of imaging an object while rotating, along a predetermined orbit around a predetermined rotation axis, the X-ray tube, the first detector, and the second detector, and to generate second projection data based on an output from the second detector, and the apparatus further comprises positional shift correction circuitry configured to correct the second projection data by using the positional shift and the imaging direction in the rotational imaging, and reconstruction circuitry configured to reconstruct volume data based on the corrected second projection data.
The X-ray imaging system performs rotational imaging, rotating the X-ray tube and both detectors around a subject. The system generates image data from both detectors. Because the smaller detector might shift, the system corrects its image data using the measured positional shift and the rotation angle. Finally, the corrected image data from the smaller, higher-resolution detector is used to reconstruct a 3D volume image of the subject. This differs from claim 2 in that it does not explicitly mention generating second projection data in association with rotational imaging with respect to an object.
9. The apparatus according to claim 1 , further comprising image generation circuitry configured to generate an indicator point image including the indicator points based on the first projection data, wherein the positional shift detection circuitry is further configured to detect the indicator points on the indicator point image and to detect the positional shift by using the detected indicator points and the predetermined positional relationship.
The X-ray system creates an image showing the indicator points (markers) on the smaller detector using the initial image data from the larger detector. It then finds these markers in the image and uses their positions to calculate the positional shift of the smaller detector, based on the known marker positions.
10. The apparatus according to claim 9 , wherein the indicator points are markers mounted on the second detector or structures forming the second detector, and the indicator points have a characteristic pattern including a transmitting region and a non-transmitting region with respect to the X-rays.
The indicator points (markers) on the smaller detector can be physical objects attached to the detector or parts of the detector's structure. These markers are designed with a pattern of areas that either block or allow X-rays to pass through. This creates a distinct pattern in the X-ray image for easy detection.
11. The apparatus according to claim 10 , wherein a rear surface side of the indicator points is configured to transmit the X-rays.
The indicator points previously described are designed such that the back of the indicator points are configured to transmit X-rays.
12. The apparatus according to claim 9 , wherein the positional shift detection circuitry is further configured to detect the positional shift by executing template matching or cross-correlation with respect to the indicator point image and a predetermined template image.
The system finds the indicator points in the X-ray image by using pattern matching techniques. It compares the image to a pre-made template image of the marker pattern, using either template matching or cross-correlation methods. This identifies the markers and determines the detector's position.
13. The apparatus according to claim 1 , further comprising a counterweight configured to compensate for a difference in a barycentric position of the second detector between a first state in which the second detector is retracted from an X-ray irradiation range associated with the first detector and a second state in which the second detector is arranged in front of the first detector, and a support mechanism configured to movably support the counterweight and the second detector.
To keep the X-ray system balanced when the smaller detector is moved in front of the larger one, the system uses a counterweight. This weight balances the change in weight distribution. A support mechanism allows both the detector and counterweight to move, maintaining the system's stability.
14. The apparatus according to claim 13 , wherein the counterweight has a point-like shape, and the support mechanism is configured to support the counterweight so as to make the counterweight movable in a direction opposite to a moving direction of the second detector between the first state and the second state and so as to locate the counterweight on one side or two sides of the first detector.
The counterweight is small and point-like. The support mechanism moves this weight in the opposite direction of the smaller detector when it's moved in front of the larger one. The counterweight can be positioned on one or both sides of the larger detector.
15. The apparatus according to claim 13 , wherein the counterweight has a rod-like shape, and the support mechanism is configured to support the counterweight so as to make the counterweight movable in a direction opposite to a moving direction of the second detector between the first state and the second state and so as to surround the first detector.
The counterweight is shaped like a rod. The support mechanism moves this rod-shaped weight in the opposite direction of the smaller detector when it's moved in front of the larger one. The rod is positioned to surround the larger detector.
16. The apparatus according to claim 1 , further comprising positional shift correction circuitry configured to correct a position of a collimator configured to limit an X-ray irradiation range or a positional shift of a compensation filter configured to attenuate a dose of the X-rays in accordance with the imaging direction.
The X-ray system can adjust the position of the collimator (which shapes the X-ray beam) or the compensation filter (which adjusts the X-ray dose) based on the imaging direction. This corrects for any shifts in these components during imaging.
17. The apparatus according to claim 1 , further comprising positional shift correction circuitry configured to correct a positional shift in a projection direction in which three-dimensional image data acquired in advance is projected, based on the imaging direction and the positional shift.
The system can correct the projection direction of previously acquired 3D images based on the current imaging direction and any positional shift of the detectors. This ensures that the projected 3D image aligns correctly with the current X-ray image.
18. The apparatus according to claim 17 , wherein the three-dimensional image data is volume data acquired in advance by at least one of the X-ray diagnostic apparatus, an X-ray computed tomography apparatus, a magnetic resonance imaging apparatus, and a nuclear medical diagnostic apparatus.
The 3D image used for projection can be a volume dataset acquired from various sources, including the current X-ray system, an X-ray CT scanner, an MRI machine, or a nuclear medicine scanner.
19. The apparatus according to claim 18 , wherein the projection data generation circuitry is further configured to generate second projection data based on an output from the second detector in association with rotational imaging of imaging an object while rotating, along a predetermined orbit around a predetermined rotation axis, the X-ray tube, the first detector, and the second detector, and to generate third projection data by projecting the three-dimensional image data along the corrected projection direction, and the apparatus further comprises a display to display a superimposed image obtained by superimposing the third projection data on the second projection data.
The X-ray system previously described creates image data from the smaller detector during rotational imaging. It also projects the pre-existing 3D image along the corrected projection direction. Finally, the system combines (superimposes) the projected 3D image with the image data from the smaller detector and displays the combined image.
20. The apparatus according to claim 1 , wherein the second detector has a higher spatial resolution than the first detector.
The second detector has a higher spatial resolution than the first detector.
21. An X-ray diagnostic apparatus, comprising: an X-ray tube configured to generate X-rays; a first detector configured to detect the X-rays; at least one second detector including a detection surface narrower than a detection surface of the first detector; a support mechanism configured to support the second detector so as to make the second detector movable between a position at which the second detector is arranged in front of the detection surface of the first detector and a retraction position at which the second detector is retracted from a field of view associated with the first detector; a support arm configured to support the X-ray tube, the first detector, and the support mechanism; imaging control circuitry configured to execute first imaging of an object while arranging the second detector at the retraction position and rotating the support arm along a predetermined orbit around a predetermined rotation axis and to execute second imaging of the object while arranging the second detector in front of the detection surface of the first detector and rotating the second detector along the orbit around the rotation axis; image generation circuitry configured to generate a first image based on an output from the first detector in the first imaging and to generate a second image based on an output from the second detector in the second imaging; positional shift detection circuitry configured to detect a positional shift of the second detector relative to the first detector, in accordance with an imaging direction by detecting projection images of the object on the first image and on the second image; and positional shift correction circuitry configured to correct a positional shift of the second image by using the positional shift corresponding to the imaging direction.
An X-ray imaging system uses an X-ray tube to generate X-rays and a first detector to capture the main X-ray image. A second, smaller detector is used, with a detection surface narrower than the first detector. A support arm supports these components. The system takes two sets of images. First, it images an object with the smaller detector retracted. Second, it takes another set of images after the smaller detector is moved in front of the first detector. A computer detects and corrects for positional shifting based on projection images.
22. The apparatus according to claim 21 , wherein the positional shift detection circuitry is further configured to detect the object by applying template matching or cross-correlation to the first image and the second image.
The X-ray system finds the object in both the first and second images by using pattern matching techniques. It compares the images using either template matching or cross-correlation methods. This identifies the object's location and determines the detector's position.
23. A medical image processing method, comprising: storing first projection data obtained from a first detector; storing second projection data obtained from a second detector and having a higher spatial resolution than the stored first projection data, and storing a projection image of at least one indicator point provided on a rear surface of the second detector; detecting a positional shift of the second projection data relative to the first projection data, in accordance with an imaging direction by using the first projection data and a predetermined positional relationship between the at least one indicator point and a plurality of detection elements in the second detector; correcting the second projection data by using the imaging direction and the positional shift; and reconstructing volume data based on the corrected second projection data.
A method for processing X-ray images involves storing data from a first detector and higher-resolution data from a second detector. It also stores the image of indicator points on the second detector. The method detects the positional shift of the second detector's data relative to the first, using the known positions of the indicator points. The second detector's data is then corrected based on the imaging direction and detected shift, and volume data is reconstructed using the corrected second detector data.
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November 25, 2014
April 4, 2017
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